The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

WA cop bashing video release delayed

The WA Court of Appeal has reserved its decision on the release of CCTV footage of a former policeman apparently shown punching and kneeing a prisoner in the head.

The footage was revealed during public hearings held by the state's corruption watchdog into alleged misconduct by police at the Broome watch-house after two alleged violent arrests involving the same officer this year.

The footage showed the officer appearing to drag one man through the station by the neck, then punching and kneeing another inmate who was shown flying headfirst onto a concrete floor while handcuffed.

The arrests prompted the state's Corruption and Crime Commission (CCC) to investigate, and Commissioner Roger Macknay ordered the footage could be released to the media.

Karen Vernon, the lawyer for the former policeman whose name has been suppressed, lodged a Supreme Court injunction against the release.

Justice Andrew Beech rejected all three grounds of the appeal in June, saying he did not accept that the commissioner had erred.

But Ms Vernon lodged an appeal against that decision, which was heard on Monday.